Messages in this thread | | | Date | Fri, 14 Jan 2022 01:09:16 -0800 | Subject | [syzbot] possible deadlock in f2fs_write_checkpoint | From | syzbot <> |
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Hello,
syzbot found the following issue on:
HEAD commit: 57c149e506d5 Add linux-next specific files for 20220110 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=15cb8b77b00000 kernel config: https://syzkaller.appspot.com/x/.config?x=2f1cca5543ac6349 dashboard link: https://syzkaller.appspot.com/bug?extid=0b9cadf5fc45a98a5083 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
Unfortunately, I don't have any reproducer for this issue yet.
IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+0b9cadf5fc45a98a5083@syzkaller.appspotmail.com
============================================ WARNING: possible recursive locking detected 5.16.0-rc8-next-20220110-syzkaller #0 Not tainted -------------------------------------------- f2fs_ckpt-7:2/4139 is trying to acquire lock: ffff88807c598390 (&sem->internal_rwsem#2){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2149 [inline] ffff88807c598390 (&sem->internal_rwsem#2){+.+.}-{3:3}, at: f2fs_write_checkpoint+0x535/0x5d00 fs/f2fs/checkpoint.c:1615
but task is already holding lock: ffff88807c599338 (&sem->internal_rwsem#2){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2149 [inline] ffff88807c599338 (&sem->internal_rwsem#2){+.+.}-{3:3}, at: __write_checkpoint_sync fs/f2fs/checkpoint.c:1744 [inline] ffff88807c599338 (&sem->internal_rwsem#2){+.+.}-{3:3}, at: __checkpoint_and_complete_reqs+0xdd/0x360 fs/f2fs/checkpoint.c:1764
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(&sem->internal_rwsem#2); lock(&sem->internal_rwsem#2);
*** DEADLOCK ***
May be due to missing lock nesting notation
1 lock held by f2fs_ckpt-7:2/4139: #0: ffff88807c599338 (&sem->internal_rwsem#2){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2149 [inline] #0: ffff88807c599338 (&sem->internal_rwsem#2){+.+.}-{3:3}, at: __write_checkpoint_sync fs/f2fs/checkpoint.c:1744 [inline] #0: ffff88807c599338 (&sem->internal_rwsem#2){+.+.}-{3:3}, at: __checkpoint_and_complete_reqs+0xdd/0x360 fs/f2fs/checkpoint.c:1764
stack backtrace: CPU: 0 PID: 4139 Comm: f2fs_ckpt-7:2 Not tainted 5.16.0-rc8-next-20220110-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2956 [inline] check_deadlock kernel/locking/lockdep.c:2999 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5027 lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 down_write+0x90/0x150 kernel/locking/rwsem.c:1514 f2fs_down_write fs/f2fs/f2fs.h:2149 [inline] f2fs_write_checkpoint+0x535/0x5d00 fs/f2fs/checkpoint.c:1615 __write_checkpoint_sync fs/f2fs/checkpoint.c:1745 [inline] __checkpoint_and_complete_reqs+0xea/0x360 fs/f2fs/checkpoint.c:1764 issue_checkpoint_thread+0xdf/0x250 fs/f2fs/checkpoint.c:1795 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK>
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